Sinclair jnr believes Gartshore was no more than an “acquaintance” of his great-grandad.

Sinclair Upton pictured next to his grandfather's gravestone in Old Monkland Cemetery

But counsel for Moira’s family, Jonathan Brown QC, told the exhumation hearing at Airdrie Sheriff Court: “Alexander Gartshore would have known of the death and would have driven past the cemetery on his bus.

“There is also the curious comment he made to a colleague after being reinstated to his job when he was released from prison.

“Mr Gartshore’s colleague Cliff Harper remarked to him that he was a very lucky man and must have many friends. He replied that he didn’t have many friends but that ‘Sinky’ had done him a good favour.

“‘Sinky’ was Sinclair Upton. That is enough to give rise to a suspicion, and the ground-penetrating radar work done at the site does nothing to dispel that.”

Mr Brown also noted that Sinclair snr was buried on a Tuesday, but the grave was excavated on the Saturday morning. Sheriff Frank Pieri allowed the exhumation after noting that no interested party had objected.

Police arrested Gartshore in 1993 over Moira’s disappearance. He denied any involvement and was never charged.

Gartshore was then implicated in Moira’s murder in 1999 by one of his friends, caged paedophile James Gallogley.

In a deathbed confession in Peterhead jail, Gallogley claimed he and Gartshore killed Moira with a third man. He said they abused her at a local bus depot after drugging her with chloroform, and that her death had been an accident.

Detectives treated the case as a missing persons inquiry for decades. But in July this year, the Record revealed that Lord Advocate Frank Mulholland had ordered police to reopen the case as a homicide.

The Strathclyde force said yesterday: “Following a court hearing, Strathclyde Police has been instructed to undertake an exhumation of a burial plot within Old Monkland Cemetery.”

The task will involve the exhumation and reburial of Sinclair snr, as well as Elizabeth Upton, who died in 1908, Joseph Thom (1923), Margaret Upton (1951), Elizabeth McNeilly (1976), Peter McNeilly (1978), Hugh Winterbottom (1985) and Mary Winterbottom (1995).

Police said: “A detailed strategy, endorsed by the Crown Office, has been prepared.

“This process is expected to take several days and will involve highly skilled personnel trained in the techniques required for this type of work.

“This is a very sensitive issue and we have been liaising with the families to ensure they are kept informed.”

Moira’s sisters, Janet and Marjory, have provided DNA for any comparisons needed.